Another round of sneaker waves are forecast for this morning and early afternoon on the Northern California coast, which means beachcombers are advised to use caution and not be fooled by an ocean that appears calm.

"We think there will be some sneaker wave behavior, meaning that a person could be fooled by the ocean on Saturday," National Weather Service spokesman Troy Nicolini said. "We think it's kind of a moderate case, but it's not a well-known science. We're the first office in the nation trying to forecast them."

Sneaker waves are large waves that seem to come out of nowhere during calm conditions. They can catch people off-guard and quickly pull them into the ocean. Survival is unlikely because of strong currents, turbulent surf and very cold water, according to a National Weather Service press release.

In the past few months, a Shelter Cove woman, a Freshwater family and a man walking on the beach near Point Reyes all lost their lives after being swept out to sea by sneaker waves.

Today's waves are forecast to be about 12 feet high.

People are encouraged to stay away from steep beaches including Big Lagoon, Fresh Water Lagoon and Agate Beach among others, said Kevin Harder, a ranger at Patrick's Point State Park and Water Safety Coalition member.

"Those are just unique beaches and really have no place whatsoever for recreation," Harder said. "Things can go wrong so quick."

Beaches such as Clam and Moonstone are a safer bet, Harder added.

Humboldt County is prone to sneaker waves because of the steep coastline and unpreparedness. He said when many people visit local beaches, they are wearing boots and parkas, and aren't ready to swim in the cold water.

"It's not that we get a lot of waves, it's just the sneaker waves mixed with the deep slope and how people's behavior on the coast is," Nicolini said.

He said that while sneaker waves are common in Humboldt County, they impact the coast from San Francisco into Canada.

The waves are caused by offshore storms that generate big waves. When the waves travel 3,000 miles to the Northern California coast, they bunch up into little groups. The bunching then leads to the behavior that creates the waves.

The National Weather Service encourages beachcombers to take the following safety tips: choose your beach well, avoid rocks and jetties, stay back, never turn your back on the ocean and don't go in after dogs.